Writing support

ABSTRACT

An erasable writing pad is formed from a transparent or translucent plastic sheet, e.g. of polyvinylchloride, whose front surface is embossed with rows of hemispherical bulges of about 0.1 mm diameter and a mutual separation equal to or less than that diameter, the rear surface of the sheet carrying a grating overlain by a distinctive color layer.

United States Patent Inventor Robert Hamelin 17 Boulevard Bentrand,Caen,Ca1vados, France Appl. No. 777,552 Filed Nov. 18, 1968 PatentedApr. 13, 1971 Priority Nov. 17, 1967 France 128640 WRITING SUPPORT 5Claims, 2 Drawing Figs.

11.8. CI 35/66 Int. Cl B431 1/10 Field of Search 35/61, 66,

Primary ExaminerHarland S. Skogquist Attorney-Karl F. Ross ABSTRACT: Anerasable writing pad is formed from a transparent or translucent plasticsheet, e.g. of

polyvinylchloride, whose front surface is embossed with rows ofhemispherical bulges of about 0.1 mm diameter and a mutual separationequal to or less than that diameter, the rear surface of the sheetcarrying a grating overlain by a distinctive color layer.

Patented 'April 13, 1971 3,574,956

Robert HAMELIN INVEN'IOR (KM 6R0 Attorney WRITING SUPPORT My presentinvention relates to an improved support on which one can write by usingan instrument such as pencil, chalk, crayon or the like depositing solidparticles on the surface thereof.

Conventional supports of this type consist essentially of a plate ofnatural slate or black cardboard.

It is the principal object of the present invention to provide animproved support of this general character.

The support according to this invention comprises a transparent ortranslucent sheet of plastic material whose front side, to be engaged bythe writing instrument, has a grained surface.

According to a specific feature of this invention, this sheet furtherhas a backside printed or coated with a backgroundforming color layer onwhich there is printed, before the background impression is applied aguiding cross-ruling pattern or grating which will on the one handremain visible by transparency when the user looks from the front and onthe other hand stand out in clear contrast against said background.

According to a further feature of my invention, this writing support orpad may comprise a stack of several sheets including a rear sheet actingas a backing layer, an intermediate stiffening sheet, and a plasticfront sheetas described above constituting the writing surface, thesevarious sheets being assembled by high frequency welding along theirmarginal portions.

Other features and advantages of this invention will appear as thefollowing description proceeds with reference to the accompanyingdrawing illustrating diagrammatically by way of example the manner inwhich the present invention may be carried out in practice. In thedrawing:

FIG. 1 illustrates a writing support according to this invention; and

FIG. 2 is a considerably magnified view of the grained plastic sheet. 7

As already explained hereinabove, a writing support designed to replaceconventional slates" consists of a transparent or translucent plasticsheet A grained by calendering and having printed on its backside on theone hand a guiding cross-ruling pattern B and on the other hand abackground-forming layer C.

Thus, the cross-ruled pattern visible by transparency from t the frontside will stand out clearly against said background.

I have found that the characteristics of the graining are of primaryimportance when it'i's desired on the one hand to make the reading aseasy as possible, i.e. with the formation of visually unbroken lines,and on the other hand to facilitate the erasing as the depositedparticles constituting the writing or other symbols remain on the linesof the grained pattern or structure.

-After exhaustive tests, I finally adopted a grained surface' consistingof fine hemispherical projections having for example the followingdimensions: diameter d=0.l mm, height h=0.05 mm.

Moreover, the distance e between adjacent rows of grains shall notexceed the value of the grain diameter d.

The improved writing support embodying this invention may be made fromheat-weldable material, notably highfrequency-fusible synthetic resinsuch as PVC. It is also recommended to reinforce this supporting sheetwith other layers or sheets to form the aforedescribed stack.

This support may be folded along a median line XX so that the writingsurface is protected during transportation.

Of course, the backside of the sheet A may be grained to register withthe front side graining. However, it is preferred to leave this backsideplain or smooth, in order to facilitate the printing of the cross rulingB and background C.

lclaim:

1. A support on which one can write by using an instrument of the typedepositing solid particles when rubbed thereagainst, such as pencil,chalk, crayon, comprising a transparent or translucent plastic sheethaving a front side, which is to be engaged by the instrument,substantially covered by rows of bulged hemispherical grains of adiameter of about 0.l mm, said sheet having its backside printed orcoated with a color layer acting as a background after guidingcross-ruling has been printed thereon.

2. A support as defined in claim 1 wherein the height of said grains isabout 0.05 millimeter.

3. A support as defined in claim 1 wherein the distance between twoadjacent rows of grains is less than 0.1 millimeter.

4. A support as defined in claim 1 wherein said sheet consists ofthermally fusible synthetic resin.

5. A support as defined in claim 4 wherein said resin is PVC.

2. A support as defined in claim 1 wherein the height of said grains isabout 0.05 millimeter.
 3. A support as defined in claim 1 wherein thedistance between two adjacent rows of grains is less than 0.1millimeter.
 4. A support as defined in claim 1 wherein said sheetconsists of thermally fusible synthetic resin.
 5. A support as definedin claim 4 wherein said resin is PVC.